High intensity light source



Dec. 11, 1945. c. G. sun's 9 ,8

HIGH INTENSITY LIGHT SOURCE Filed July 11, 1941 Inventor: Chauncey G. Suits,

b HIS Attorney.

Patented Dec. 11, 1945 HIGH INTENSITY LIGHT SOURCE Chauncey G. Suits,- Sche to General Electric New York nectady, N. Y., assignor Company, a corporation of Application July 11, 1941, Serial No. 401,985 8 Claims. (01. 24011.2)

The present invention relates to an improved form oi high intensity light source.

Considerable success has been attained in procuring high luminous intensities by means of an arc discharge operating in a high pressure gaseous atmosphere, one example of a light source of this kind being the quartz-enclosed mercury lamp with an operating pressure of several atmosheres. An ultimate limitation appears to be imposed on the intensities realizable with this type of lamp, however, by the tendency of the mercury discharge under extreme operating conditions to devitriiy the quartz container and thus to destroy its light-transmitting quality and impair its strength.

It is an object of the present invention to provide a high pressure luminous arc source which is not subject to a limitation of this kind, and in this connection an important feature of the invention consists in the provision of means for maintaining a discharge in a vapor-filled space which is directly bounded by a liquid under pressure, preferably a pressure of at least several atmospheres. This is accomplished in a typical embodiment of the invention by circulating a suitable liquid, for example, water, about the interelectrode space within which the discharge is es tablished.

It is found that this procedure permits the creation of a highly concentrated are having very great luminous intensity. Moreover, this is accomplished in a manner which ail'ords very full protection to the container in which the discharge is established and prevents impairment of the containers light-transmitting quality even after a long period of operation of the apparatus.

A further feature of the invention comprises the use of means for continually circulating the high pressure fluid through the discharge container and for imparting rotary motion to the fluid as it passes the active portion 01' the arc. The first expedient assures the continuous re-. moval of heat and of deleterious discharge products, while the second has the effect of stabilizing the discharge and of maintaining it in fixed relation with respect to the walls of the container The aspects oi the invention which I desire to protect herein are pointed out with particularity in the appended claims. The invention itself, together with further objects and advantages there- 01, may best be understood by reference to the following description taken in connection with the drawing, in which Fig. 1 is a side elevation of an apparatus suitably embodying the invention; Fig. 2 is a longitudinal section oi the operative parts of the apparatus of Fig. 1 (these parts being rotated from the position which they occupy in Fig. 1; Fig. 3 is a sectional view taken on line 33 01' Fig. 2; Fig. 4 is an enlarged view of certain of the elements 01' Fig. 2; and Fig. 5 is a sectional view illustrating a modification of the invention.

The light-emitting portion 01' the illustrated apparatus is that which'is indicated at I. in Figs. 1 and 2. This comprises a tubular member which consists of a light-transmitting substance, preferably quartz, and which encloses the mutually spaced extremities of discharge-sustaining electrodes l2 and I3. solid carbon type, or, alternatively, they may be "cored carbons" oi the general character described in E. A. Sperry Patent 1,227,210, granted May 22, 1917. In the latter case the core of the negative electrode should be of such character as to increase its electron emissivity, while the core of the positive electrode, or anode, may advantageously contain a material which is adapted to enhance the luminosity of the interelectrode discharge, for example, cerium oxide.

The quartz member In is supported at its ends by tapered cylindrical parts I5 and I8, the resulting joints being sealed by compressible gaskets indicated at i! and [8. The parts I! and I6 bear integral flanges 20 and 2| and are compressed against the ends of part I0 by means of a series of bolts 23 cooperating with these flanges.

Each of the parts l5 and It connects at its end with a smaller tubular member (25 and 26), the joints between these parts being formed by'means of adapters 28 and 29. The parts 25 and 26 are made of sufficient length and internal dimensions so as readily to receive within them the inactive ends of the electrodes l2 and i3, these electrodes being initially introduced by means of removable closure elements 32 and 33 provided at the respective extremities of the parts 25 and 26. The construction of one of these closure elements is illustrated at the upper portion of Fig. 2 and is shown to include, in addition to the part 32, a piston 38 which is slidably supported in the part 32 and which is biased in the upward direction by means of a compression spring 36. As the piston 35 moves upwardly, either through the action of the spring 36 or under the influence of unbalanced pressure existing within the apparatus, it compresses a gasket member 31 which is confined between the piston and a cooperating element 39 surrounding the piston shaft. By this means a fluid-tight seal may be established, the quality of which tends to improve as the internal pres- These electrodes may be of the sure within the apparatus increases. When it is desired to remove the closure element 32 for the purpose of replacing the electrode I2, this may be readily accomplished by first applying pressure to the enlarged head 42 provided on the piston shaft and by this means moving the piston in a downward direction to relieve the closure member from the frictional restraint which would otherwise be imposed on it by the compressed gasketi'i and the element 39.

Within the member I the electrode I2 is supported by means of a bracket 44 which has as an integral part thereof a resilient arm 46. This arm supports one of two cooperating drive Wheels 48 and 49 between which the electrode I2 is frictionally retained (see Fig. 3), the spring action of the arm 46 being sufficient to assur tight engagement of the electrode by the drive wheels. A similar pair of drive wheels 5| and 52, similarly mounted, support the electrode I3. The wheel 48 may be positively driven by means of an externally accessible drive shaft 53 which is sealed through the wall of the container part I5 by the use of a packing gland indicated at 54, and a similar drive shaft 55 is provided in connection with the wheel 52. By rotation of the shafts 53 and 55 it is possible to move the electrodes I2 and I3 longitudinally and by this action to control their relative positions. During use of the apparatus, the position and feeding of the electrode may be automatically egulated by any appropriate mechanism such, for example, as that which is disclosed in Heinrich Beck Patent 1,313.666, granted August 19, 1919.

In the operation of the apparatus, unidirectional potential is applied between the electrodes I2 and I3 by means of terminal connections indicated at 51 and 58, the circuit to the electrodes being completed through the metallic structure of the mounting brackets and drive wheels described above. The polarity of the applied potential should be such as to make the electrode I2 a cathode and the electrode I3 an anode. In order to initiate operation, the electrodes may be brought into momentary contact and then drawn apart to establish a discharge between them. It is this discharge (indicated at 59) which is re sponsible for the light emission of the apparatus.

In order that the discharge between the electrodes I2 and I3 may be converted into a highly intense luminous arc, there is provided about the arc-containing space a continuous sheath 62 of liquid under pressure. To this end the container part I6 is provided with a fluid inlet connection 60, and a corresponding outlet connection 6| is i provided in conjunction with the part 25. The liquid supply may comprise, for example, a tank of water (not shown) which is maintained under a pressure of from fifty to several hundred pounds per square inch. For reasons which will be explained shortly, it is preferred to cause the high pressure liquid to be continuously circulated through the discharge chamber, a thing which can be readily done by connecting a suitable cations an improvement, in the matter of confin- I electrodes. The fact that a continuous sheath of water exists between the arc and the vitreous container I0 fully protects the container from deterioration due to excessive heat and from other destructive effects of the arc. Moreover, the continuous motion of the fluid as it is circulated through the apparatus permits the removal of products of the discharge which might otherwise tend to obscure the arc and to lessen the emission of light. It is found that with a liquid pressure of pounds or more a light intensity on the order of one million lumens or better can be realized.

It is, of course, desirable that the are be confined to the central region of the discharge chamber, and in this connection it is helpful to provide means for producing rotary motion of the circulating liquid as it passes the region within which the arc exists. This may conveniently be done in one way by the use of a spiral baille or vane structure 65 (see Fig. 4) at the entrance end of the arc chamber. This structure, which is mounted in a conforming sleeve 66, has the effect of imparting a whirling motion to the liquid as it passes upwardly through the structure, which motion continues as the liquid proceeds through the enclosure I0 and past the discharge space. This expedient is found very effective in preventing the arc discharge from coming into contact with the surface of the transparent container part II].

A still further alternative, and for some appliing the arc discharge comprises the modified construction which is illustrated in'Fig. 5, in which elements corresponding to parts previously described bea similar numerals, differentiated by priming. In this case the discharge chamber is provided Within a cylindrical glass member III which is clamped between the tapered extremities of cooperating metallic parts I5 and I6. At its central portion the member III is provided with an inwardly directed indentation III which serves as an abutment for a disk H having a central opening I2 through which a discharge between electrodes I2 and I3 may pass and through which the high pressure liquid 62' may flow. The disk II is of a highly refractive substance such as asbestos lumber and has the effect of fixedly centering the arc discharge. Its effectiveness in this respect may be further augmented, if desired, by"

the provision of a helical baflle 65 having the purpose and function of the correspondingly numbered element described in connection with Fig, 2

While water is considered to be the preferred liquid for the purposes of the present invention because it has no objectionable solid products of dissociation and because the vapors produced when it dissociates in contact with carbon are adapted to sustain an arc of good'luminous quality, other liquids may obviously be employed. For example, one may use in this connection a substance such as glycerine Moreover, although the invention has been described by reference to a particular structural path between them and a liquid under a pressure of at least several atmospheres disposed about and in contiguity with the said discharge path, whereby an are occurring between the said electrodes is caused to exist in a vapor-filled space bounded directly by the said liquid.

2. The method of generating light by means of an arc discharge between mutually spaced electrodes which comprises passing a discharge current between the electrodes while the discharge space is enclosed in a sheath of liquid under a pressure of from fifty to several hundred pounds per square inch and in direct contiguity with the resultant arc.

3. A light source comprising a container having a lighttransmitting wall part, mutually spaced electrodes within the container and providing a discharge path in proximity to the said wall part, and a liquid under pressure of at least several atmospheres within the container and disposed about the said discharge path, whereby an are occurring between the said electrodes is caused to exist in a vapor-filled space bounded directly by the said liquid.

4. A high intensity light source comprising a container having a light-transmitting wall part, mutually spaced electrodes within the container and providing a discharge path in proximity to the said wall part, and means for circulating a liquid under pressure through the container and about the said discharge path, whereby an arc discharge passing between the said electrodes is caused to exist in a vapor-filled space bounded' directly by the said liquid,

5. A high intensity light source comprising a container which consists at least in part of a hollow tubular member of light-transmitting character, spaced electrodes within the container and providing a discharge path within the said hollow tubular member, and means for circulating a liquid under pressure through the said tubular member in direct contiguity with the space defining the discharge path.

6. A high intensity light source comprising a container having a light-transmitting wall part, mutually spaced electrodes within the container and providing a discharge path in proximity to the said wall part, means for introducing a liquid under pressure i-nto the said container and for circulating the liquid with a rotary motion about the said discharge path, whereby an are discharge passing between the said electrodes is confined to a vapor-filled space bounded directly by the said liquid.

7. A light source comprising a container having a light-transmitting wall part, means including spaced electrodes within the container for establishing an arc discharge in proximity to the said wall part, means for circulating a liquid under pressure through the container and in di- .-rect contiguity with the said discharge, and means including a helical vane system positioned to impart rotary motion to the liquid as it passes the interelectrode space within which the arc discharge occurs.

8. A light source comprising a container having a light-transmitting part, spaced electrodes within the container for establishing a luminous arc discharge in proximity to the said part, a member positioned transversely to the discharge path and having a restricted opening through which the discharge passes, thereby to stabilize the discharge, and means for circulating a liquid under pressure through the container and through the said opening, whereby the region within which the discharge occurs comprises a vapor-filled space bounded directly by the liquid.

CHAUNCEY G. SUITS. 

